With the wheat harvest set to begin within a week, farmers are pressing for a resolution of the federal investigation of genetically-modified wheat plants found growing in eastern Oregon.

Japan and South Korea, the two largest buyers of soft white wheat grown in Oregon, Washington and Idaho, have suspended wheat purchases. Both countries reject genetically-modified food, and do not want to buy transgenic wheat.

That leaves Oregon growers wondering if they'll have problems selling this summer's crop, valued annually at $300 million to $500 million. Questions about storing and shipping wheat remain unanswered, and growers don't know if they'll have to pay for tests to prove their wheat is not genetically modified.

In meeting with the U.S. Department of Agriculture in mid-June, Oregon wheat industry representatives said foreign buyers want direct communication regarding the investigation. The agency appears to be responding by sharing more information with customer nations than it had before, said Blake Rowe, chief executive of the Oregon Wheat Commission.

Part of the USDA's job, Rowe said, is to help farmers maintain good relations with customers.

"It's an absolutely vital thing that needs to happen quickly," he said.

Japan and South Korea wanted more information than the USDA released in news releases and website postings, Rowe said. When customers representing 50 percent of the market ask for direct communication, he said in a June 20 letter to the USDA, "You pick up the telephone and find out what they need and how to address their concerns."

Rowe believes Oregon farmers will be allowed to truck grain from their fields to port silos, but it's unclear whether the export markets will accept shipments.

"You can't store the whole harvest," he said.

Testing Oregon wheat for genetically-modified material before it's exported may be part of the solution, said Steve Mercer, vice president for communications for U.S. Wheat Associates, a Virginia-based marketing organization.

Japan now tests wheat for residue of more than 100 chemicals, Mercer said.

"They are very deliberate and disciplined buyers," he said, and quite capable of doing additional tests for the presence of genetically-modified material. "What form it would take, and who would handle the cost down the road, who knows?"

Although Japan and South Korea postponed new purchases of soft white wheat, the decision did not affect orders that were already on the books. Another big customer, Taiwan, placed an order in mid-June and did not exclude western wheat, Mercer said.

Meanwhile, Oregon Sen. Ron Wyden announced he'll discuss the problem with growers and commodity officials in the Pendleton area on Tuesday. Wyden is chairman of the International Trade Subcommittee of the Senate Finance Committee.

The investigation is being carried out by the USDA's Animal and Plant Health Inspection Service, or APHIS. Investigators say they have not found any GM plants outside the original field and say there is no evidence transgenic grain entered the commercial stream. Investigators have tested samples from farms and seed companies.

The findings announced so far, however, only deepen the mystery. They were a "Roundup Ready" wheat variety developed by Monsanto Co. to resist its glyphosate-based herbicide. Field tests ended years ago, and the variety was never approved for commercial planting. It should not have been growing anywhere.

Wheat industry officials acknowledge the investigation may lack a tidy conclusion: APHIS may not be able to completely explain how the plants ended up in the eastern Oregon field.

"The more uncertainty there is," said Rowe of Oregon Wheat Commission, "the more we'll have to discuss it to figure out what to do."